Production of ammonium nitrate from ammoniacal gases.



* OFFICE- imam cannon; or camels, GERMANY.

rnonuc'rion or Ammonium mans mom AMMONIACAL eases.

1,053,456.. No Drawing To all whom, it may concern:

Be it known that I, Fmsmucn Unnn, a subject of the German-Emperor. residing at Get-the, \Vestphalia, Germany, have invented certain new and useful Improvements in the Production of Ammonium Xitrate from Ammoniacal Gases; and I do hereby declare that the following is a full and exact description thereof.

This invention relates to the extraction of ammonia from industrial gases. especially from the distillation gases of coke ovens or as plants. However the invention may also e applied to gases of other origin for instance to the ammoniaeal gases wlnch may be distilled oil' from the so-called gas water or from other impure ammoniaeal solutions.

The invention consists broadly in introducing the said gases as hot as possible into a watery solution of an alkali earth nitrate after se )arating from the hot gases the tar eventua lv contained therein. Besides ammonia these gases contain considerable quantities of carbon dioxid and sulfureted hvdrogen and therefore react under the a mre named conditions for example with a solution of calcium nitrate according to the following equation aslamentsums+col+bcataolumm The resulting insoluble calcium carbonate is precipitated and may be filtered oil. The tlltrate contains dissolved almost pure ammonium nitrate which may be easily obtained by evaporatin the solution.

I am aware that it has been previously proposed to absorb gases from coal distillation in earth alkali nitrate solutions and to separate in this manner the ammonia contained in the uses in the form of ammonium nitrate. But as prior inventors have cooled down the gases far below the boilingpoint of water in order to permit the tar and the water to be separated from the gases, the conditions were such that the im urities which are always contained in intustrial gases, particular compounds of sulfur and ciyanogen, and 0t or compounds, almost no- (eterminable by chemical analysis were either as such absorbed b the absorbin cold solution or caused t e formation 0 other im urities in said solution.

Accor ing to my present invention the tar only, but not the water vapor, is separated from the hot gases, and the ases are conducted into the earth alkali nitrate solution Specification of Letters Patent.

Application tiled December 18, 1911.

Patented Feb. 18,1913.

Serial No. 666,620.

while having such a temperature that the solution acquires a temperature of approximately 100 C. In continuing my process in the above described manner I succeed in obtaining an ammonium nitrate of excellent purity suitable for instance for the n-oduction of explosives for which the Pl'Ot uct obtained by the above-mcntioncd known process is by no means serviceable without special rectification.

Because of the high temperature of the gases and of the absorbin solution the sulfureted hydrogen which ierctofore caused contamination of the solution is not absorbed. I believe that it is iartly for the same reason that the other known or unknown impurities of the gases either pass through the solution unabsorbed or are temporarily absorbed and then immediately reexpelled.

A further advantage of my process consists in that the apparatus and materials for cooling and drying the gases are dispensed with. Nevertheless, a more concentrated and therefore more irotitablc solution is obtained than by the known irocess. Furthermore, by not separatin the water from the gases and not considcra )ly reducing the temperature of the gases I avoid the withdrawal of a considerable quantity of ammonia from the gases, as it is the case in the known process, that is to say. in my access the gases are not diluted with regar 'to the ammonia. and therefore I need no apparatus for distilling oil the ammonia from the ammoniaeal water.

In cuntradistinction to the known methods my prtwess is suitable for absorbing diluted as well as highly concentrated gases. Idspccially, I may employ it for separating the ammonia contained in the so-eallcd gaswater.

It is true that the product obtained by the almve-indicated process accordin" to my invention is far purer than the prmbict obtained by the known process, but sometimes it may nevertheless contain traces of impurities. In this case the product is hygroscopic and slowly assumes a gray or brown color and a prickling smell. In order to eliminate these impurities and to obtain a product quite equivalent to that obtained from pure chemicals I may modify my process in the following manner: After the absorption of the gases by the earth alkali nitrate solution has been terminated and irecipitate cyanogen and oth'ergcompoundsare expelled and by evaporatingtlie elation, Ifdircctly obtain onan; industriallsealea substantially approximately 1.2 metersof water and its average tem )eratnre may be. about 95% C. It may be (istllled off from common gaswater containing 1% of ammonia. The absorptiontakes place rapidly'until the solution is perfectly saturated. 'lhe temperatnre of the solution rises within a short time from ".30 to about 05 C. The reaction is finished in about 25 minutes. The saturated solution the volume of which remains practically unehan ml is filtered'ofl' from the precipitate whi e'still hot, slightly acidulated and heated. A reaction with slight. development of gases takes olaec. 13y evaporating the solution tlms obtained a white, inodoroas and barely hygroscopic product is obtained. The properties of the )l'OdllCt do not alter when it is kept instocc for a long time. in contradistinction to the pro crties of the known technical product. on y very small traces of calcium nitrate, usually not more than 0.03", are found in my product.

I elaim:-

1. The process of producing ammonium nitrate from ammoniacal gases substantially free from tar which comprises absorbin such Fases havin a temperature of approximatey 100 C. y a solution ot'an earth alkali nitrate, so that the temperature of oagfrem gniej t-lie s0lution during the greater part of the I -;absorptio1i ;i\p])1foxiiiiates 100 C., wherefiltrate landa-islightidevelo after the solution is filtered .oil' and evapofrated, substantially as described.

;2. The process of producing ammonium hitrhtflfromcoal-distillation gases, which process comprises separating the tar only but not'the water vapor from the hot'gases, conducting the gases into an earth alkali nitrate solution the temperature of the gases being such that the solution obtains a temperature of approximately 100 C., filtering oil and evaporating the solution, substan tially as described.

3. The process of producing ammonium nitrate from annnonizu-al gases substantially free from tar, which process comprises ab- St3ll)lllg such gases \vhile-haviiu a temperature of appro.\'imatcl 100 C. by a solution of an earth alkali nitrate so that the tei'nperature of the solution during the greater part. of the absorption approximates 100 0., whcreafter the solution is filtered oil, slightly acidulated and evaporated, substantially as described.

-l. The process of prodturin anuuoniuiu nitrate from coal -dist-illation gases. which process comprises separating from the gases, while still hot, the tar only but not. the water vapor, conducting the gases into an earth alkali nitrate solution the temperature of the gascs'being such that the solution ohtains a temperature oi approximately 100" C., filtering oil, slightly acidulat-int, and evaporating the solution, substantially as described.

1'3. The process of producing ammonium nitrate from ammoniacal gases substantially free .from tar which comprises absorbing such gases in a heated condition by a hot solutionot an earth alkali nitrate, filtering the resulting solution. and evaporating the samesubstantially as descrilwd.

' In testimony whereof I ntiix my signature in presence of two witnesses.

FRIEDRICH UllDl' Witnesses:

Copie: of thin patent may be obtained (or iivo cents each, by addressing the Commissioner 0! Patents, Washington, D. 0." 

